Etymology 1
From mould (“loose friable soil; rotting earth regarded as the substance of the human body”) + -er (suffix forming frequentative verbs), probably influenced by mould (“furry growth of fungi”).[1] Mould is derived from Middle English mold, molde (“loose friable soil, dirt, earth; earth as the substance out of which God made man, and to which the human body decays into after death”),[2] from Old English molde (“earth, soil”), from Proto-Germanic *muldō (“dirt, soil; furry growth of fungi, mould”), from Proto-Indo-European *melh₂- (“to crush, grind”).
Verb
moulder (third-person singular simple present moulders, present participle mouldering, simple past and past participle mouldered) (British spelling)
- (transitive, intransitive) To decay or rot.
- 1772–1782, William Mason, The English Garden:
- [Time's] gradual touch / Has moulder'd into beauty many a tower.
1817 December 20 (date written), Biographical Notice of the Author; published in Northanger Abbey: And Persuasion. […], volume I, London: John Murray, […], 20 December 1817 (indicated as 1818), →OCLC, page v:And when the public, which has not been insensible to the merits of "Sense and Sensibility," "Pride and Prejudice," "Mansfield Park," and "Emma," shall be informed that the hand which guided that pen is now mouldering in the grave, perhaps a brief account of Jane Austen will be read with a kindlier sentiment than simple curiosity.
1842, Henry Wadsworth Longfellow, “[Miscellaneous.] The Rainy Day.”, in Ballads and Other Poems, 2nd edition, Cambridge, Mass.: […] John Owen, →OCLC, stanza 1, page 111:The day is cold, and dark, and dreary; / It rains, and the wind is never weary; / The vine still clings to the mouldering wall, / But at every gust the dead leaves fall, / And the day is dark and dreary.
c. 1855, John Brown’s Body:John Brown's body lies a-mouldering in the grave, but his soul goes marching on!
2022 January 12, Philip Haigh, “Okehampton should be the start of railway restoration”, in RAIL, number 948, page 50:Today the trackbed moulders, although Lancashire council reports that it's largely intact to around 1.5 miles south of Fleetwood.
Etymology 2
From mould (verb) + -er (suffix forming agent nouns).
Noun
moulder (plural moulders) (British spelling)
- A person who moulds dough into loaves.
- Anyone who moulds or shapes things, including in a mould.
1944 November and December, A Former Pupil, “Some Memories of Crewe Works—II”, in Railway Magazine, page 342:It was, however, most interesting work, and the moulders themselves were a decent crowd, never tired of making jokes about themselves such as the hoary one that moulders did not live long, which however ran counter to the other one that no germs could live in a foundry—the atmosphere was too foul.
- A machine used for moulding.